1. Field of the Technology
The present technology relates generally to bilateral hearing prostheses, and more particularly to data transmission through a recipient's skull bone.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the cochlea are impeded, for example, by damage to the ossicles. Individuals suffering from conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As a result, individuals suffering from conductive hearing loss typically receive a prosthetic hearing device that generates mechanical motion of the cochlea fluid. For example, acoustic energy may be delivered through a column of air to the tympanic membrane (eardrum) via a hearing aid residing in the ear canal. Mechanical energy may be delivered via the physical coupling of a mechanical transducer (i.e. a transducer that converts electrical signals to mechanical motion) to the tympanic membrane, the skull, the ossicular chain, the round or oval window of the cochlea or other structure that will result in the delivery of mechanical energy to the hydro-mechanical system of the cochlea.
Individuals suffering from conductive hearing loss typically receive an acoustic hearing aid, referred to as a hearing aid herein. Unfortunately, not all individuals who suffer from conductive hearing loss are able to derive suitable benefit from hearing aids. Furthermore, hearing aids are typically unsuitable for individuals who suffer from single-sided deafness (total hearing loss only in one ear). Hearing aids commonly referred to as “cross aids” have been developed for single sided deaf individuals. These devices receive the sound from the deaf side with one hearing aid and present this signal (either via a direct electrical connection or wirelessly) to a hearing aid which is worn on the contra lateral (or, in other words, the ipsi lateral or opposite) side of the recipient's head. Unfortunately, this requires the recipient to wear two hearing aids. Additionally, in order to prevent acoustic feedback problems, hearing aids generally require that the ear canal be plugged, resulting in unnecessary pressure, discomfort, or other problems such as eczema.
As noted, hearing aids rely primarily on the principles of air conduction. However, other types of devices commonly referred to as bone conducting hearing aids or bone conduction devices, function by converting a received sound into a mechanical force. This force is transferred through the bones of the skull to the cochlea and causes motion of the cochlea fluid. Hair cells inside the cochlea are responsive to this motion of the cochlea fluid and generate nerve impulses which result in the perception of the received sound. Bone conduction devices have been found suitable to treat a variety of types of hearing loss and may be suitable for individuals who cannot derive sufficient benefit from hearing aids, cochlear implants, etc., or for individuals who suffer from stuttering problems.